The present invention relates to an IC card and a method for rewriting its program, and more particularly to a down-loadable IC card which is capable of rewriting its program quickly and a method for rewriting its processing program.
`IC cards` are now being used in a wide variety of applications. The IC cards used to process several kinds of transactions store individual data contents to be processed by different processing procedures. Therefore, the processing programs for the IC cards are unique to the terminals or host computers (hereinafter represented by terminals) in which they are employed.
For this reason, there has been proposed `down-load processing` IC cards in which processing programs may be written to the IC card the terminals corresponding to several transactions including bank transactions.
These IC cards include a rewritable non-volatile memory in an information memory portion portion for storing a processing program; and thus if the operation of an IC card is desired to be changed, its program can be rewritten.
However, such a system has the following problem. In writing or rewriting a program for the IC card belonging to the above class, the IC card has instructions dedicated to effecting a high speed transfer for programs of about 1 to 8 K bytes. In the block transfer, blocks of about 10 to 80 bytes are transferred creating a long overhead time. And also, even if the program is to be partially rewritten, the IC card is adapted so that the program has to be wholly rewritten, which takes a comparatively longer time than rewriting only the portion to be changed.
The program may include an application program and some parameters necessary for execution thereof. The parameter include constants, identification codes of the card and a user. Moreover, since a large amount of data must be transferred at a high speed in order to rewrite the program, the transfer error detection system also becomes complicated.